An 11-year-boy who had been playing football with two friends was shot dead outside a pub in Liverpool last night by a teenager who rode past on a BMX bike with his face obscured by a hood.

The boy was hit in the neck after three shots were fired outside the Fir Tree pub in Croxteth at around 7.30pm, in the latest in a spate of violent attacks on young people around the country.

Paramedics worked to try to save the victim, who was dressed in his football kit, and he was said to be in a critical condition when he arrived at Alder Hey hospital. He was later confirmed dead.

Witnesses close to the scene suggested that the attack had been carried out by a local gang member who is believed to be 12 years old.

Merseyside police described it as an "awful ... senseless killing", and appealed to the residents to help find the culprit.

The home secretary, Jacqui Smith, sent her condolences to the boy's family. She said: "I am shocked and saddened to hear about this tragic shooting. My thoughts are with the victim's family and friends."

The killing again highlights the escalating problem of youth crime in Britain. In London alone 17 teenagers have been murdered this year, and in Manchester there have been two high-profile shootings including the death of 15-year-old Jessie James, who was gunned down while cycling through a park last year. It is not the first shooting in Croxteth, where a 17-year-old boy was shot in the leg in March.

There was a large police presence in Croxteth last night, with riot vans and officers guarding a cordoned-off area. One parent described hearing a loud bang. "Nobody thought anything more of it, but as we walked past the pub we noticed a young boy slumped in the corner of the car park. Somebody shouted out that he had been shot and a few parents tried to resuscitate him."

Another resident said that he had heard that three boys were playing football when a young man cycled up on a BMX and fired three shots. "One bullet hit a car, one missed, and one hit that boy," he said.

The Croxteth Park Estate, which was built in the mid 80s, was formerly the biggest private housing estate in western Europe. The area around the pub was made a "designated area" by police last year, after residents raised concerns about teenagers gathering outside.

Earlier in the day the Tory leader, David Cameron, said Britain was facing a "real and growing problem" of violence which grew "in the fertile soil of antisocial behaviour" and required a comprehensive response involving the police, the courts and society at large.